Sheet metal forming apparatus



July 5, 1966 J. l. CARLSON, SR 3,258,948

SHEET METAL FORMING APPARATUS Filed Nov. 1, 1963 2 Sheets-Sheet, 1

FIGI

y l6 1 H J 6 26 I INVENTOR JOHN I H03 CARLSON,SR.

ATTORNEY y 1966 J. CARLSON, SR 3,258,948

SHEET METAL FORMING APPARATUS Filed Nov. 1, 1963 2 Sheets-Sheet. 2

1 mhhhhhh FIG 4 INVENTOR,

JOHN l. CARLSONSR.

BY I (M7 ATTORNEY United States Patent M 3,258,948 SHEET METAL FORMINGAPPARATUS John I. Carlson, Sr., New Britain, Conn., assignor to GeneralElectric Company, a corporation of New York Filed Nov. 1, 1963, Ser. No.320,731 9 Claims. (Cl. 72---57) My invention relates to sheet materialforming apparatus, and more particularly to sheet material formingapparatus utilizing elastomeric or rubber-like die members.

The use of elastomeric or rubber-like material as a die member has comeinto substantial use in connection with sheet metal forming primarilybecause the use of this material for a die is substantially lessexpensive than constructing a metal die by conventional metal machiningmethods. In accordance with prior art elastomeric metal formingtechniques, a sheet of metal to be formed is laid on a bed ofelastomeric material, and a forming punch is brought down against themetal, forcing it into the bed of elastomeric material and causingportions of the sheet to be folded up around the punch, forming thedesired bend or bends.

In order to get satisfactory sharp bends, it has been necessary toprovide the body of elastomeric material with grooves in the uppersurface thereof, along the intended bendline of the metal, and to placethe workpiece on the elastomeric material so that the intended bendlineof the workpiece coincides with the grooves provided in the elastomericmaterial. While it is possible, with such prior art technique, to use asingle bed of elastomeric material to form bends in workpieces ofdifferent sizes, this requires provision of grooves in the surface ofthe material at each of the desired bendlines as previously described,and the accurate placement of the workpieces thereon in each case,

Also, in accordance with prior art, if it is desired to use a single bedof elastomeric material to bend workpieces of different sizes, a bedmust be provided which is large enough to handle the largest piece to bebent. This adds substantially to the expense of the equipment, anddetracts from its efficiency, since it may be only once in a great whilethat such a large piece is desired to be bent. In addition, the largesize of such a bed of elastomeric material makes it inconvenient to Workwith smaller size workpieces.

It is an object of the present invention to provide metal formingapparatus of the elastomeric bed type, which does not require theprovision of pre-cut grooves in the surface of the elastomeric materialand corresponding placement of the workpiece on the elastomericmaterial.

It is another object of the invention to provide metal forming apparatusof the elastomeric bed type which has a high degree of flexibility andis capable of handling sheet metal workpieces of a variety of sizeswithout requiring substantial time and labor in setting up the equipmentor in changing from one size to another.

It is another object of the invention to provide metal forming apparatusof the elastomeric bed type which is comparatively inexpensive andutilizes only a relatively small amount of elastomeric material.

In accordance with the invention in one form, sheet metal formingapparatus is provided including a die member comprising a bed or body ofelastomeric material which is contained within a heavy, generallytray-shaped, metallic support or casing providing a bottom wall andupstanding side walls and an open top wall. The casing is supported forlimited rocking or pivotal movement about an axis extending parallel tothe intended bendline.

3,258,948 Patented July 5, 1966 The die member comprising the casing andthe bed of elastomeric material is normally supported in a substantiallyhorizontal position by spring means, whereby when a punch member isbrought down against a workpiece laid on top of the elastomericmaterial, the workpiece is gripped between the punch and the uppersurface of the elastomeric material as the die member is rocked aboutits pivot, compressing the spring. A portion of the workpiece is bent asmall amount about a corner of the punch member as the die member rocksunder the downward pressure of the punch. Continued downward movement ofthe punch member after the die member reaches the limit of its rockingmovement completes the bending action by forcing the workpiece a shortdistance further into the elastomeric material, causing the elastomericmaterial to bulge slightly around the edge of the punch, folding thebent portion of the workpiece around the edge of the punch.

In accordance with the invention in another form, a pair or elastomericdie bed assemblies are supported in spaced apart co-planar relation,whereby a workpiece may be laid so as to expand partially onto each diebed assembly, and a pair of punch members are brought downsimultaneously thereby forming two bends at once.

In accordance with another aspect of the invention, means is providedfor moving the two elastomeric die bed assemblies toward and away fromeach other, together with their corresponding punch members, whereby thedistance between the two bends to be made simultaneously may beselectively adjusted within a predetermined range.

The invention will be more completely understood from the followingdetailed description, and its scope will be pointed out in the appendedclaims.

In the drawings:

FIGURE 1 is an elevation view of one embodiment of the inventionpartially incross-section, showing the die members in their normalpositions;

FIGURE 2 is an elevation view similar to FIGURE 1, showing the diemembers in their actuated or depressed position;

FIGURE 3 is a plan view of the apparatus of FIG- URES 1 and 2, and

FIGURE 4 is anelevational view of another embodia ment of the invention.

FIGURE 1 illustrates a metal bending apparatus in accordance with oneembodiment of this invention wherein a pair of die assemblies, generallyindicated by 1 and 2 are mounted upon a base member 3 for cooperationwith vertically movable punches 4 and 4A carried by a press ram 4B. Eachdie structure is identical with the other; therefore, only one will bedescribed in detail. Each die structure includes a casing or containerhaving a bottom wall 9 and surrounding, upwardly extending side walls 10which form .a generally rectangular upwardly opening cavity 11. Thecavity 11 is filled with elastomeric material 8. Thus the elastomericmaterial is effectively confined while leaving the upper or workingsurface open. The upper surface of the elastomeric material ispreferably made to project a small amount, such as 36 above thecorresponding surfaces of the adjacent side walls of the casing 6.

Each casing 7 is pivotally mounted on the corresponding support member 6by means of a pair of trunnions 20 and 21, which extend through openings22 and 23 in the side of the support member 6 and are received inrecesses 24 and 25 in the casing (as best shown in FIGURE 3). The casing7 is biased to an upper position by means of coil springs 26 which aremounted in recesses 27 provided in the support member 6 and similarrecesses 28 provided in casing 7. While the casings 7 are guided by thetrunnions 20, 21, however, the primary bearing surfaces are provided byportions 6A of the support 6 and 7A of the casing 7.

Downward movement of the punches 4 and 4A causes them to engage theupper surface of the workpiece 5 and to press it against the uppersurface of the elastomeric material 8. Continued downward motion of thepunches rocks each of the die assemblies comprising the casings 7 andthe elastomeric material about their respective pivotal supports,compressing the springs 26. At the same time, a part bend is formed inthe workpiece at each of the outer corners 29 and 30 of the punches 4and 4A. This fixes the position of the workpiece with respect to thepunches, so that no lateral shifting can occur as the process continues.

The casings then bottom against the supports 6. The punches 4 and 4Acontinue to travel a short distance, however, forcing the workpiecefurther into the elastomeric material adjacent the corners of thepunches, and completing the bending action. In this connection, itshould be noted that the elastomeric material bulges slightly along theouter surface of the corners 29 and 30, as at 31, 32 respectively,thereby assisting in making a sharp bend.

In accordance With the invention, the die members are made horizontallyadjustable. For this purpose, each support member 6 is formed with apair of horizontally extending slots 12 and 13 which fit about upwardlyextending rails 14 and 15 provided on the base member 3. Each diestructure is provided with an outwardly extending threaded shaft 16which is rotatably attached to the support 6 at one end by means of abracket 16A and extends through a threaded opening 17 provided in ablock 18 mounted on the base member 3. A manually operable handle 19 isattached to the outer end of the threaded shaft 16 to facilitatehorizontal movement of the die structure.

While the corners 29 and 30 of the punch have been shown as beingright-angled, it has been found that they may be formed as acute angles,and the upward bulges 31 and 32 of elastomeric material will bend theworkpiece 5 at an angle in excess of 90. This may be desirable to allowfor the workpiece springing back a small amount after it has been bent.Other modifications of the shape of the punch may also be made,particularly at or near the outer corner portions without affecting theoperation of the invention.

At the conclusion of the bending process, the punch 4 is raised and thesprings 26 force the casings 7 upwardly to the position shown in FIGURE1 and the formed Workpiece is removed. It may be noted from FIGURE 3that the trunnions and 21 and the bearing surfaces 6A and 7A are spacedfrom the outer edges of the punches 4, 4A. With this arrangement,downward movement of the punch 4 causes the tiltable casings 7 to rotatedownwardly and slightly outwardly, carrying the elastomeric material 8with them. Since the upper surface of the elastomeric material 8 is inintimate contact with the workpiece 5, the downward and outward tiltingof the casings 7 causes the elastomeric material to exert an outwardlydirected force on the workpiece. The outwardly directed force on theworkpiece at each side keeps the center of the workpiece taut andprevents any buckling even though there is no support directly under thecenter portion.

In FIGURE 4, the invention is shown as embodied in metal formingapparatus comprising a pair of punch and die assemblies 35, 36. Each ofthe punch and die assemblies 35, 36 comprises a base support member 37carrying a pair of guiding posts 38. Since FIGURE 4 is an end elevationview of the assembly, the pair of supporting posts 38 of each assembly35, 36 are in alignment, and

therefore only one post of each assembly may be seen in this view.

Slidably supported on the posts 38, is an upper support member 39 havinga pair of holes 40 adapted to receive the posts 38. The upper supportmember 39 also carries a plurality of headed bolts 41, the heads ofwhich are received in generally T-shaped slots 42 in a member 43 whichmay comprise the vertically movable portion of a press or which maycomprise a plate attached to such movable portion.

The base support member 37 carries a die supporting block 43 rigidlyattached thereto by suitable means, not shown, which in turn hingedlysupports the elastomeric die assembly comprising a rigid tray-likecasing 44 containing a block or bed of elastomeric material 45. The

- casing 44 is normally held in a substantially horizontal position bymeans of a relatively heavy compression spring 46. The upper supportmember 39 carries a punch member 47 adapted to cooperate with theelastomeric material 45.

In accordance with this aspect of the invention, means is provided foradjusting the relative positions of the punch and die assembly 35 and36, without disturbing the preset relationship between the punch members47 and the die members 45. For this purpose, an elongated threadedadjusting rod 50 is provided, which is rotatably journalled in asupporting block 51 midway between the assemblies 35, 36. The rod 51)has one portion extending through the base support 37 of the punch cardand die assembly 36, and an oppositely directed portion extendingthrough the base portion 37 of the punch and die assembly 35. Therespective halves of the rod 50 are threaded in opposite directions, sothat rotation of the rod 50 in one direction, such as by the wheel 52having a handle 53, causes the punch and die assemblies 35, 36 to movetoward each other, and in the opposite direction causes them to moveaway from each other. The adjusting movement of the punch and dieassembly 35, 36 toward and away from each other is facilitated by theslidable mounting of the upper support members 39 in the member 43 bymeans of headed bolts 41 riding in T-shaped slots 42, as previouslydescribed. Comparable slidable guiding means, not shown, is alsoprovided for the base members 37 on their support plate. Followingadjustment of the spacing between the punch and die assemblies 35, 36,the upper support members 39 are fixedly anchored in place by suitablemeans such as by clamping nuts threaded onto the bolts 41, or by othersuitable means, and the base support member 37 is likewise fixedlyanchored to its support by suitable means.

While the adjustable die structure shown in FIGURE 4 is shown as usedwith the preferred form of elastomeric die construction, it will bereadily obvious that the aforesaid adjustable die structure may be usedwith conventional rigidly-supported metal bending dies in place of theelastomeric material 45.

Other modifications of the invention will also occur to those skilled inthe art, and I therefore intend by the appended claims to cover all suchmodifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Sheet material forming apparatus comprising:

(a) a support;

(b) a casing having a bottom wall and peripheral upstanding side wallsdefining a cavity therein;

(c) resilient means supporting said casing on said support;

(d) a body of elastomeric material filling said cavity and having agenerally planar surface thereof exposed to receive a workpiece of sheetmaterial thereon;

(e) punch means disposed and arranged to engage said workpiece when onsaid exposed surface of said body of elastomeric material and to causepivotal movement of said casing against said resilient support wherebyto force said workpiece partially into said body of elastomeric materialand to bend a portion of said workpiece around a corner of said punch.

2. For use with metal bending apparatus having a movable punch forforming bends in a workpiece, a die apparatus comprising:

(a) a support;

(b) a rigid casing pivotally supported on said support,

said casing having a bottom and peripheral upstanding side wallsdefining an open-top recess;

(c) a body of elastomeric material filling said cavity and having asurface thereof exposed at said open p;

(d) stop means carried by said support, and

(e) resilient means supporting said casing in a normal position spacedaway from said stop means, whereby a sheet material workpiece may beplaced on said exposed surface and pressed by said punch against saidbody of elastomeric maerial, rotating said casing about said pivotalsupport and against said stop to form said workpiece around said punch.

3. For use with sheet material bending apparatus including a movablepunch for forming bends in a workpiece, a die assembly comprising:

(a) a support;

(b) a casing having a generally planar bottom wall and peripheralupstanding side walls defining an opentop recess;

(c) a body of elastomeric material filling said recess and having asurface portion thereof exposed at said open top;

(d) means supporting said casing on said support for pivotal movement,said casing having the outer portion of one of said side walls formed toprovide an elongated pivotal bearing surface extending substantially thesame length as the corresponding dimension of said elastomeric body;

(e) stop means carried by said support, and

(f) means resiliently supporting said casing on said support with saidexposed surface of said elastomeric body extending substantially in ahorizontal plane.

(4. Sheet material bending apparatus comprising:

(a) a support;

(b) a pair of casing members pivotally supported on said support, eachof said casing members comprising a generally planar bottom Wall andperipheral upstanding side walls defining an open-top recess;

(c) a body of elastomeric material substantially filling each of saidrecesses;

(d) means supporting said casings on said support for pivotal movementabout parallel axes, said axes extending adjacent the outer edges ofeach of said casing members respectively;

(e) stop means limiting said pivotal movement of said casings, and

(f) means resiliently supporting each of said casing members with saidexposed surface of said elastomeric material extending substantially ina common plane.

5. Sheet material bending apparatus comprising:

(a) a support;

(b) a pair of casing members, each of said casing members comprising agenerally planar bottom wall and peripheral upstanding side wallsdefining an open top recess;

(c) a body of elastomeric material substantially filling each of saidrecesses;

(d) means supporting said casings on said support for pivotal movementabout parallel axes, said axes extending adjacent the outer edges ofeach of said casing members respectively;

(e) stop means limiting said pivotal movement of said casings;

(f) means resiliently supporting each of said casing members with saidexposed surfaces of said bodies 6. of elastomeric material extendingsubstantially in a common plane;

(g) and means for adjustably positioning said casing members closer orfarther away from each other whereby to accommodate workpieces ofvarying sizes.

6. Sheet material bending apparatus as set forth in claim 5 wherein saidadjusting means comprises a shaft journalled for rotation on saidsupport substantially midway between said punch-and-die assemblies andhaving a first portion thereof in threaded relation with a first one ofsaid assemblies and a second portion thereof in threaded relation withthe other of said assemblies, said portions being threaded in oppositedirections, and means for rotating said shaft to adjustably positionsaid assemblies.

7. Sheet material bending apparatus comprising:

(a) a pair of spaced supports;

(b) a casing member pivotally mounted on each of said supports, saidcasing comprising a generally planar bottom wall and peripheralupstanding side Walls defining an open-top cavity;

(c) a body of elastomeric material filling each of said cavities andhaving a generally planar surface thereof exposed at said open top;

(d) resilient means supporting each of said casing members with saidexposed surface of said elastomeric material extending in asubstantially common plane;

(e) the pivotal axes of said casings on said supports extending parallelto each other and adjacent the outer edges of said casings, and

(f) means for adjustably positioning said supports closer to or fartheraway from each other.

8. Sheet material bending apparatus comprising:

(a) a support;

(b) a pair of punch and die assemblies supported on said support, eachof said punch and die assemblies comprising a base plate and at leastone vertically extending guide post supported on said base plate, apunch supporting member disposed in vertically spaced relation over eachof said base plates and having a hole therein adapted to receive saidguide post;

(c) punch means carried by each of said punch support members and havinga predetermined relationship to said die member;

(d) a casing member pivotally mounted on each of said base plates, saidcasing comprising a generally planar bottom wall and peripheralupstanding side walls defining an open-top cavity;

(e) a body of elastomeric material filling each of said cavities;

(f) resilient means supporting each of said casing members;

(g) the pivotal axes of said casings on said base plates extendingparallel to each other and adjacent the outer edges of said casings, and

(h) means for moving at least one of said punch and die assemblies withrespect to the other of said punch and die assemblies on said supportwithout disturbing said predetermined relationship of each of saidpunches with respect to the corresponding die member.

9. Sheet material bending apparatus comprising:

(a) a support;

(b) a pair of punch and die assemblies supported on said support, eachof said punch and die assemblies comprising a base plate and at leastone vertically extending guide post supported on said base plate, apunch supporting member disposed in vertically spaced relation over eachof said base plates and having a hole therein adapted to receive saidguide post;

(c) punch means carried by each of said punch support members and havinga predetermined relationship to said die member;

(d) a casing member pivotally mounted on each of said base plates, saidcasing comprising a generally planar bottom wall and peripheralupstanding side walls defining an open-top cavity;

(e) a. body of elastomeric material filling each of said cavities;

(f) resilient means supporting each of said casing members;

(g) the pivotal axes of said casings on said base plates extendingparallel to each other and adjacent the outer edges of said casings, and

(h) means for simultaneously moving said pair of punch and dieassemblies selectively toward and away from each other at substantiallyequal rates of speed Without disturbing said predetermined relationshipof each of said punches with respect to the corresponding die member toselectively vary 2 the distance between said bends While maintainingsymmetrical relationship of said bends with respect to a predeterminedcenter line.

References Cited by the Examiner UNITED STATES PATENTS 1,268,360 6/1918Kimball.

2,362,006 11/1944 Herzog 723 96 2,390,803 12/1945 Marschner 724OO2,443,596 6/1948 Cahill 72396 3,045,327 7/1962 Clarke et a1.

FOREIGN PATENTS 690,007 4/ 1953 Great Britain.

OTHER REFERENCES Modern Metals: September 1960, vol. XVI, No. 8, page56.

CHARLES W. LANHAM, Primary Examiner.

R. D. GREFE, Assistant Examiner.

1. SHEET MATERIAL FORMING APPARATUS COMPRISING: (A) A SUPPORT; (B) ACASING HAVING A BOTTOM WALL AND PERIPHERAL UPSTANDING SIDE WALLSDEFINING A CAVITY THEREIN; (C) RESILIENT MEANS SUPPORTING SAID CASING ONSAID SUPPORT; (D) A BODY OF ELASTOMERIC MATERIAL FILLING SAID CAVITY ANDHAVING A GENERALLY PLANAR SURFACE THEREOF EXPOSIED TO RECEIVE AWORKPIECE OF SHEET MATERIAL THEREON; (E) PUNCH MEANS DISPOSED AREARRANGED TO ENGAGE SAID WORKPIECE WHEN ON SAID EXPOSED SURFACE OF SAIDBODY OF ELASTOMERIC MATERIAL AND TO CAUSE PIVOTAL MOVEMENT OF SAIDCASING AGAINST SAID RESILIENT SUPPORT WHEREBY TO FORCE SAID WORKPIECEPARTIALLY INTO SAID BODY OF ELASTOMERIC MATERIAL AND TO BEND A PORTIONOF SAID WORKPIECE AROUND A CORNER OF SAID PUNCH.